Display tile with increased display area

ABSTRACT

A display tile having a frame whose compliance is increased in a well determined region to accommodate the different thermal expansions of the frame and one or more substrates to which the frame is fastened. The display tile has also regions of increased compliance that will deform to allow different parts of the frame to be brought into contact and glued to the lateral sides of two superimposed substrates when at least one lateral side of one of the substrates is not coplanar with the corresponding lateral side of the other substrate.

The present invention relates to a frame for a display or display tile,a display or display tile itself, or a method of constructing such aframe for a display or display tile.

BACKGROUND

FIG. 1 shows a schematic representation of a tiled display.

The display tiles T can be an emissive display apparatus like e.g. aLiquid Crystal Display apparatus or it can be a rear projection displayapparatus.

FIG. 1 also shows schematically how the picture elements or pixels P arearranged on the display tile T. Three sub-pixels green, red and blue lieclose to one another and produce in their totality a picture element ofthe image displayed. The picture elements follow one another with aspacing A. The broken line indicates the inner area of the display tileT on which an image can be formed and viewed by a viewer. The spacebetween the broken line and the edges of a display tile T is anon-display area. The non-display area often corresponds to a spaceoccupied by a bezel B whose primary function is to hold the LCD panel ofthe LCD in position. In the prior art the spacing between two adjacentpicture elements P displayed onto adjacent display tiles T is largelydetermined by the distance separating two adjacent display tiles T andthe width of the bezel B. The space between the display areas of twoadjacent display tiles is often referred to as the seam (SEAM). Theminimum distance between two adjacent display tiles T depends on theclearance needed to allow thermal and humidity expansion of the displaytiles T without misalignment, bowing or damaging of the Liquid Crystalpanel (or projection screen) of the display tile T.

The problem of thermal and humidity expansion and the relative movementof tiles with respect to each other and its impact on the inter-tileseams is well known in the art too.

The width of the bezel can be decreased or the bezel can be eliminatedas e.g. proposed in U.S. Pat. No. 8,446,540 “Display device having anenlarged display area”.

The problem is that the solution may not be reliable for large liquidcrystal panels (e.g. with more than one meter of diagonal) as the weightof the panel could overcome the forces exerted by the “fixing member”and “panel guide portion”.

Another problem is that the panel guide portion may not be in metal toavoid scratching the liquid crystal panel. Therefore, it needs to bethick enough to withstand the forces applied on it. The seam will thusbe at least twice as wide as the panel guide portion will be thick.

The author of U.S. Pat. No. 8,446,540 also excludes the use of adhesivetape to fasten the liquid crystal panel to a frame because it isincompatible with reliability and durability of the assembly.

The reliability and durability could be improved if the adhesive tapewere thick enough.

For instance, with values of α-aluminum=23.8-10⁻⁶ 1/K andα-glass=8.1·10⁻⁶ 1/K (α being the coefficient of thermal expansion) anda total bond length at room temperature of L0=1500 mm for a change intemperature of ΔT=40 K a difference in length at both ends ofΔL=ΔT·L0/2·(α-Al-α-Glass)=0,471 mm will occur in a stress-free assembly(i.e. when aluminum and metal are not bonded together). A pressuresensitive mounting tape with a thickness of 0.8 mm should be suitable tocompensate Δα-induced stress in this configuration.

But such a thickness of pressure sensitive mounting tape is notcompatible with a seam of less than 1 mm.

The art also does not provide solutions for reliably fastening a liquidcrystal panel affected by tolerances (e.g. a mismatch between thelateral dimensions of the glass panel delimiting the liquid crystallayer) while at the same time avoiding the use of a bezel or rim.

There is a need to improve the art.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a frame for adisplay or display tile, a display or display tile itself, or a methodof constructing such a frame for a display or display tile.

A frame for a display or display tile, a display or display tile itself,or a method of constructing such a frame for a display or display tileaccording to embodiments of the present invention may overcome one ormore of the disadvantages mentioned above.

According to an aspect of the present invention, a display tilecomprises a frame made of a first material with a first coefficient ofthermal expansion fastened to a substrate made of a second material witha second coefficient of thermal expansion by means of a heat activatedadhesive tape; the frame being characterized in that it is divided intothree parts: a first part to be glued to a lateral side of thesubstrate, a third part to serve as fastening interface to anotherstructure like e.g. a backlight element or a support structure and asecond part positioned between the first and third part to isolate thethird part from strain in the first part e.g. as strain relief.

Isolating the first part of the frame that is heated when the adhesivetape is activated from the third part of the frame that remains at alower temperature than that of the first part prevents excessivedeformation of the substrate once fastening of the frame to thesubstrate is complete.

In particular, the first coefficient of thermal expansion is preferablyhigher than the second coefficient of thermal expansion.

In particular, the first material is preferably a metal with acoefficient of thermal expansion larger or equal to 23.8 10−6 1/K. Themetal can be aluminum, for example.

In particular the second material is preferably glass with a coefficientof thermal expansion. The glass can be, for example, a borosilicateglass with a coefficient of thermal expansion lower or equal to 9.5 10⁻⁶1/K.

In a further aspect of the invention the frame is divided into two ormore frame elements or frame strips. Each frame strip has a first partto be glued to a lateral side of the substrate, a third part to serve asfastening interface to another structure like e.g. a backlight elementor a support structure and a second part positioned between the firstand third part to isolate the third part from strain in the first part,e.g. to operate as strain relief.

Isolating the third part of the frame strip from strain in the firstpart of the frame strip can be assured by one or more openings in theframe strip. The opening extends across the first and second part of theframe strip away from the substrate.

The openings can for instance be rectangular. The corners of therectangle can be rounded.

In another aspect of the invention, the third part of the (frame) stripis preferably isolated from strain in the first part of the frame stripby grooves formed, for example by etching or stamping in the frame partor by any equivalent method.

The grooves can be formed on both sides of the frame strip. The depth ofthe grooves is preferably more than half the thickness of the framestrip in the first and second part of the frame strip.

In a further aspect of the invention, a display tile comprises a framefastened to a first substrate and a second substrate by means of anadhesive tape; the frame being characterized in that it is divided into3 parts: a first part to be glued by means of the adhesive tape (e.g. aheat activated adhesive tape) to a lateral side of the first substrate,a third part to be glued by means of the adhesive tape (e.g. a heatactivated adhesive tape) to a lateral side of the second substrate and asecond part positioned between the first and third part, the second parthaving higher compliance than the first and third part thereby allowingthe first and third part to be positioned in different planes.

In another aspect a method of fabricating a frame for a display tile isprovided, the frame being made of a first material with a firstcoefficient of thermal expansion, the method comprising:

fastening the frame to a substrate made of a second material with asecond coefficient of thermal expansion by means of a heat activatedadhesive tape;

fabricating the frame in three parts:

gluing a first part by means of the heat activated adhesive tape to alateral side of the substrate, fastening a third part to anotherstructure and positioning a second part between the first and third partto isolate the third part from strain in the first part.

In another aspect a method of fabricating a frame for a display tile isprovided, the method comprising:

fastening the frame to a first substrate and a second substrate by meansof an adhesive tape;

fabricating the frame in 3 parts:

gluing a first part by means of a heat activated adhesive tape to alateral side of the first substrate,

gluing a third part by means of the heat activated adhesive tape to alateral side of the second substrate, and

positioning a second part between the first and third part, the secondpart having a higher compliance than the first and third part therebyallowing the first and third part to be positioned in different planes.

It is an advantage of that aspect of the invention that it allows aframe to be glued to a first substrate and a second substrate, the firstsubstrate being parallel to the second substrates even when at least onelateral side of the first substrate is not coplanar with thecorresponding lateral side of the second substrate.

In a further aspect of the invention grooves are formed in the secondpart of the frame; the grooves being substantially parallel to the firstand second substrates.

The grooves will increase the compliance of the frame in the desireddirection and will allow different parts of the frame to be in differentplanes.

In a further aspect of the invention the grooves are formed on bothsides of the frame.

In a further aspect of the invention the depth of the grooves is atleast 50% of the thickness of the frame.

In another aspect the invention proposes a frame for a display tile, theframe being made of a first material with a first coefficient of thermalexpansion and being fastened to a substrate made of a second materialwith a second coefficient of thermal expansion by means of a heatactivated adhesive tape; the frame being divided into three parts: afirst part to be glued by means of the heat activated adhesive tape to alateral side of the substrate, a third part to serve as fasteninginterface to another structure and a second part positioned between thefirst and third part to isolate the third part from strain in the firstpart. In a further aspect at least one opening extends from an edge ofthe frame and extends across the first part and second part of theframe. In a further aspect grooves are formed in the first part and/orthe second part of the frame. The grooves may be formed on both sides ofthe frame. The depth of the grooves may be at least 50% of the thickness(x) of the frame. In a further aspect the frame is split into two ormore frame elements or strips. Any or every feature relating to theframe can relate to one or more of the frame elements or strips.According to a further aspect said another structure is a backlightelement or a support structure.

In another aspect the invention proposes a frame for a display tile, theframe being fastened to a first substrate and a second substrate bymeans of an adhesive tape; the frame being divided into parts: a firstpart to be glued by means of the adhesive tape to a lateral side of thefirst substrate, a third part to be glued by means of the adhesive tapeto a lateral side of the second substrate and a second part positionedbetween the first and third part, the second part having a highercompliance than the first and third part thereby allowing the first andthird part to be positioned in different planes. Grooves may be formedin the second part of the frame, the grooves being substantiallyparallel to the first and second substrates. The grooves may be formedon both sides of the frame. The depth of the grooves s at least 50% ofthe thickness (x) of the frame.

In another aspect the invention proposes a display tile comprising aframe as described above.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic representation of a tiled display.

FIG. 2A shows an exploded view of a display tile, its frame and abacklight structure.

FIG. 2B shows an example of profile for a non-planar frame element.

FIGS. 3A, 3B and 3C show how the substrate and the frame are fastenedtogether by means of a heat activated adhesive tape in accordance withan embodiment of the present invention.

FIGS. 4A and 4B show the deformation of the frame and the substrateduring and after heat activation of the adhesive tape of an embodimentof the present invention.

FIG. 5 shows a first adaptation of the frame to prevent deformation ofthe substrate caused by strain in the region of the frame that is gluedto the substrate in accordance with an embodiment of the presentinvention.

FIG. 6 shows a second adaptation of the frame in accordance with anembodiment of the present invention.

FIGS. 7A and 7B illustrate the deformations of the second part of theframe.

FIG. 8 illustrates how first and second adaptation of the frame can becombined in accordance with an embodiment of the present invention.

FIGS. 9A to D illustrate a first and second substrate fastened to aframe in accordance with an embodiment of the present invention.

FIG. 10 illustrates the problem to fasten first and second substrate toa frame when the first and second substrates have different lateraldimensions and/or are misaligned.

FIGS. 11 and 11A show an adaptation of the frame to allow deformation(i.e. compliance) of the frames and to allow the frame to be glued tofirst and second substrate even when at least one lateral side of one ofthe substrate is not coplanar with the corresponding lateral side of theother substrate in accordance with an embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

The present invention will be described with respect to particularembodiments and with reference to certain drawings but the invention isnot limited thereto but only by the claims.

Embodiments of the present relate to a design of a display tile T thathas one, or some or all of the following advantages:

-   -   keeps its form and flatness,    -   has only negligible thermal expansion regardless of its        environment (high humidity, temperature fluctuations . . . )        and/or    -   will stay aligned with adjacent display tiles when used in a        tiled display.

The invention is also related to tiled displays where the width of theseam will be as small or smaller than the spacing between adjacentpixels on a display tile.

To that end, with reference to FIGS. 2, 3, 5, 9 and 11 a stabletransparent substrate 1 like for example glass is used. The substrate 1is either part of a rear projection screen or a glass plate in a liquidcrystal panel. The glass is for instance soda lime glass. Any suitabletransparent material or other types of glass are possible. Thecoefficient of thermal expansion of the material used for the carriersubstrate is advantageously lower than 9.5·10⁻⁶ K⁻¹. The substrate 1 hasa first side or entry face that is substantially planar. The entry faceis the face or side of the substrate 1 through which the light projectedby a projector or a backlight enters. The substrate 1 has a second sideor exit face that is substantially planar. The exit face is the face orside of the substrate 1 through which the light exits towards a viewer.The first side and second side of the substrate 1 are substantiallyparallel. When a line or surface, in particular a plane, is said to beperpendicular to the substrate, it means that the line or surface isperpendicular to the first and second sides of the substrate 1.

The substrate 1 is usually a parallelepiped with a first surface, asecond surface parallel to the first surface and lateral sides 1A, 1B,1C and 1D as shown in FIG. 2A.

A display (whether it is a rear projection display or an emissivedisplay like a liquid crystal display or LCD), can be a fixed formatdisplay. The substrate 1 is associated with other layers. For instancethe substrate 1 can support an optical element such as a Fresnel lensand/or a diffuser layer. The substrate 1 can also be part of an LCDpanel. In that case, the substrate 1 is but one component of a liquidcrystal panel: thin film transistors can be formed on the substrate 1; athe first glass substrate 1 and second glass substrate parallel to thefirst delimit a space to enclose a layer of liquid crystals, additionallayers like e.g. colour filters can be formed on the second surface etc.. . . . In the description of the invention below, only the firstsubstrate 1 will be explicitly mentioned. The display could also be aplasma display.

To avoid a non-display area along the perimeter of the substrate 1, thesubstrate is fastened to a frame 2 by mean of an adhesive film 3distributed along the lateral sides 1A, 1B, 1C and 1D of the substrateas shown in FIGS. 3B, 3C, 9C, 9D, 10, 11. Avoiding a non-display area isuseful both in e.g. a single panel LCD and a tiled display panel.

The frame 2 is advantageously made of metal. This allows reducing thethickness of the frame without compromising on the solidity of theassembly.

The frame can be e.g. an aluminium ribbon cut in a sheet with athickness between 0.1 mm and 1 mm. For instance, the thickness of theframe is 0.2 mm.

An example of adhesive film 3 is given in the utility modelDE202009015262U1 “Latent reaktive, hitzeaktivierbare Klebmasse and damithergestellte Klebemittel” which is incorporated herein by reference.Heat activation of the heat activated adhesive film can be done e.g. bynear infrared heating or hot air (as provided by e.g. a heat gun).

Heat activated adhesive films not being fluid like glue; it is easier tocontrol the thickness of the adhesive film 3 that will contribute to theseam between adjacent tiles.

Heat activated adhesive films are also easy to apply and cause no riskof glue penetration between layers associated with the substrate 1 orglue spilling onto one the first and/or second side of the substrate 1.This is very important because glue penetration would cause visualartefacts.

The frame 2 is not necessarily of one piece. It can for instance besplit into e.g. 2 or more frame strips (2A, 2B, 2C and 2D) asillustrated on FIG. 2A. As illustrated on FIG. 2A, several frame stripscan be glued to a lateral side of the substrate 1 (e.g. 1B). The framestrips need not be planar as illustrated by FIG. 2B that shows anexample of profile for a non-planar frame strip 2B. The frame strips(2A, 2B, 2C and 2D) are used as mechanical interface between thesubstrate 1 and a backlight structure B (in the case of e.g. a liquidcrystal display) or a support structure B (in the case of e.g. a rearprojection display). Fastening of the frame 2 to the structure B can bedone e.g. by means of screws like screw S and nuts like nut N.

A strip, e.g. 2A, is pressed against the heat activated adhesive tape 3applied to one of the lateral sides, e.g. 1A, of the substrate 1 asillustrated on FIGS. 3A and 3B. Heat and pressure are applied to theframe strip with help of e.g. a bonding head 4 as illustrated on FIG.3C. The use of a bonding head allows application of heat and pressure ina well delimited region of the frame strip (the shaded area on FIG. 3A).

When heat is applied to activate the adhesive tape 3, the frame stripheats and expands. Heating and expansion will be highest right under thebonding head. Even if the frame strip is made of a metal like e.g.aluminum, the temperature will vary across the width W of the framestrip from a higher temperature T+ to a lower temperature T−. As aresult, the frame strip will not expand uniformly as illustrated on FIG.4A. At the same time, the dimensions of the glass substrate 1, and inparticular the length of the lateral side (1A, 1B, 1C or 1D) being gluedto the frame strip (2A, 2B, 2C or 2D), will change as well but to alesser extent than the frame strip.

As it cools down, the frame strip 2A will return to its initial length,inducing deformations of the substrate as illustrated on FIG. 4B wherethe substrate 1 buckles under compressive stress by one or more of theframe strips. The impact of such deformations on the seam betweenadjacent tiles causes variations of the seam width along a seam and fromseam to seam that will make the seam between tiles more perceptible to aviewer than would otherwise be the case. In some cases, the contractioncan cause failure of the adhesive tape.

To solve this problem, the shape of the metallic frame strip is modifiedas illustrated on FIG. 5 in accordance with one embodiment of thepresent invention.

The frame strip 2 is divided in three parts: a first part 21, a secondpart 22 and a third part 23. A first part 21 will be glued to a lateralside of the substrate 1.

A second part 22 acts as a strain relief structure between the firstpart 21 and the third part 23. The second part 22 is preferably morecompliant than the other two parts, 21 and 23.

At least some strain relief is assured by one or more openings or slits5 in the frame strip. An opening 5 extends from the edge of the framestrip and extends across the first and second part of the frame strip.

The opening 5 can be shaped as a rectangle but other geometries arepossible. For instance, the corners of the opening can be rounded asillustrated on FIG. 5.

Strain relief can also be assured by grooves 6 etched or stamped in thefirst and/or second part of the frame strip as illustrated on FIG. 6.

The grooves 6 are formed, e.g. by etching on both sides of the framestrip 2 giving a corrugated aspect to the region where they are formed.

The depth of the grooves is ideally more than 50% of the thickness (x)of the frame strip.

The grooves 6 are preferably substantially perpendicular to thesubstrate 1. In other words, the angle made by a groove 6 and thesubstrate 1 is preferably 90.0 degrees of angle+/−0.1 degree of angle.Alternatively, the angle made by a groove 6 and the substrate 1 ispreferably 90.0 degrees of angle+/−0.5 degree of angle. Alternatively,the angle made by a groove 6 and the substrate 1 is preferably 90.0degrees of angle+/−1.0 degree of angle. Alternatively, the angle made bya groove 6 and the substrate 1 is preferably 90.0 degrees of angle+/−5.0degree of angle. Alternatively, the angle made by a groove 6 and thesubstrate 1 is less than 90.0 degrees of angle but more than 45.0degrees of angle.

It is also possible to combine openings 5 and grooves 6 to furtherimprove the isolation of the third part 23 of the frame strip fromstrain in the first part 21 of the frame strip. Openings 5 and groovesor corrugations 6 can be combined in different manners. An example ofhow openings 5 and grooves or corrugation 6 can be combined isillustrated on FIG. 8. In this example, the grooves 6 are etched rightunder the openings 5.

As mentioned earlier, the substrate 1 may be associated to other layersand/or substrates as is e.g. the case in a liquid crystal panel.

In that case, the different substrates and layer may have slightlydifferent dimensions as illustrated on FIGS. 9A, B, C, e.g. FIG. 9Dwhere substrate 1 is slightly smaller than substrate 7 resulting in amismatch M between the lateral side of substrates 1 and 7.Alternatively, both substrates can have close to identical dimensionsbut they can be misaligned, resulting in their lateral sides not beingcoplanar.

When the dimensions of substrates 1 and 7 differ too much and/or whenboth substrates are misaligned, it can be difficult to glue themtogether to the frame 2 (the bond may be weaker than expected or eveninexistent with one or both of the substrates). This is illustrated onFIG. 10 where a cross section of a frame strip 2A the heat activatedlayer 3 and substrates 1 and 7 are shown. As can be seen on FIG. 10, themismatch M between the substrates lateral sides 1A and 7A makes bondingof the lateral sides 1A to the frame strip very difficult or impossible.Two adhesive tapes 3A and 3B can be used on the lateral sides 7A and 1Aof substrates 7 and 1 respectively but this will not prevent that therewill be no contact between the adhesive strip 3B and the frame element2A.

A solution to that problem in accordance with an embodiment of thepresent invention is to increase the compliance (i.e. flexibility) ofthe frame element 2A in the region of the frame element that willcorrespond to the border between substrates 1 and 7. The compliance can,for instance, be increased by etching grooves 8 in the frame element asillustrated on FIG. 11, especially FIG. 11A. The depth of the grooves 8is preferably more than 50% of the thickness of the frame element 2.

FIG. 11 shows frame strip 2, the heat activated adhesive layer 3A andsubstrates 1 and 7. A heat activated adhesive tape 3A and optionally 3Bcan be used on the lateral sides 7A and optionally sides 1A ofsubstrates 7 and 1 respectively.

As shown in FIG. 11, frame 2 can be fastened to the first substrate 1and the second substrate 7 by means of an adhesive tape 3A 3B,respectively. The frame 2 is divided into 3 parts: a first part 31 whichcan be optionally glued by means of a heat activated adhesive tape 3B toa lateral side of the first substrate 1, a third part 33 to be glued bymeans of the heat activated adhesive tape 3A to a lateral side of thesecond substrate 7 and a second part 32 positioned between the first 31and third 33 part, the second part 32 having a higher compliance (i.e.better able to comply or adjust) than the first 31 and third 33 partthereby allowing the first 31 and third 33 part to be positioned indifferent planes.

The grooves 8 can be formed in the second part 32 of the frame 2, thegrooves 8 being substantially parallel to the first 1 and second 7substrates. The depth of the grooves 8 is preferably more than 50% ofthe thickness of the frame 2. The grooves 8 can be formed on both sidesof the frame 2.

The frame 2 can be split into two or more frame elements or strips 31,32, 33. A frame 2, e.g. 2A, 2B, 2C . . . that will accommodate both thethermal expansion during heat activation and the mismatch between theposition of the lateral sides (e.g. 1A and 7A) of substrates 1 and 7 canbe obtained by positioning the grooves 8 in the first part 31 of a frame2, e.g. 2A, 2B, 2C . . . . The desired deformation of the frame 2 willbe obtained with grooves 8 substantially parallel to the first andsecond substrate 1, 7 to which substrates the frame 2 is glued.

In other words, the angle made by a groove 8 and the first and secondsubstrates 1 and 7 is preferably 0.0 degrees of angle+/−0.1 degree ofangle. Alternatively, the angle made by a groove 8 and the first andsecond substrates 1 and 7 is preferably 0.0 degrees of angle+/−0.5degree of angle. Alternatively, the angle made by a groove 8 and thefirst and second substrates 1 and 7 is preferably 0.0 degrees ofangle+/−1.0 degree of angle. Alternatively, the angle made by a groove 8and the first and second substrates 1 and 7 is preferably 0.0 degrees ofangle+/−5.0 degree of angle. Alternatively, the angle made by a groove 8and the first and second substrates 1 and 7 is larger than 0.0 degreesof angle but less than 45.0 degree of angle.

1-43. (canceled)
 44. A frame for a display tile, the frame being of one piece or being split into two or more frame elements or strips, the frame being made of a first material with a first coefficient of thermal expansion, the frame being adapted to be fastened to a substrate, wherein the substrate forms part of the display tile, the substrate being made of a second material with a second coefficient of thermal expansion; wherein the one piece frame or each frame element or strip is divided into three parts: a first part to be glued to a lateral side of the substrate, a third part to serve as fastening interface to a support structure or a backlight structure and a second part positioned between the first and third part to isolate the third part from strain in the first part.
 45. The frame for a display tile according to claim 44, wherein at least one opening extends from an edge of the frame and extends across the first part and the second part of the frame.
 46. The frame for a display tile according to claim 44, wherein grooves are formed in the first part and/or the second part of the frame and/or grooves are formed on both sides of the frame.
 47. The frame for a display tile according to claim 46, wherein the depth of the grooves is at least 50% of the thickness of the frame.
 48. The frame for a display tile according to claim 44, wherein the first part is glued by means of adhesive tape to the lateral side of the substrate.
 49. A frame for a display tile, the frame being of one piece or being split into two or more frame elements or strips, the frame being adapted to be fastened to a first substrate and a second substrate, wherein the first substrate and the second substrate form part of the display tile; wherein the one piece frame or each frame element or strip is divided into 3 parts: a first part to be glued to a lateral side of the first substrate, a third part to be glued to a lateral side of the second substrate and a second part positioned between the first and third part, the second part having a higher compliance than the first and third part thereby allowing the first and third part to be positioned in different planes.
 50. The frame for a display tile according to claim 49, wherein grooves are formed in the second part of the frame, the grooves being substantially parallel to the first and second substrates and/or grooves are formed on both sides of the frame.
 51. The frame for a display tile according to claim 50, wherein the depth of the grooves is at least 50% of the thickness of the frame.
 52. The frame for a display tile according to claim 49, wherein the first part is glued by means of adhesive tape to the lateral side of the substrate.
 53. A display tile and a frame according to claim
 44. 54. A display tile and a frame according to claim
 49. 55. A method of fabricating a frame for a display tile, the frame being of one piece or being split into two or more frame elements or strips, the frame being made of a first material with a first coefficient of thermal expansion, the method comprising: fastening the one piece frame or each frame element or strip to a substrate made of a second material with a second coefficient of thermal expansion, wherein the substrate forms part of the display tile; fabricating the one piece frame or each frame element or strip in three parts: gluing a first part to a lateral side of the substrate, fastening a third part to a support structure or a backlight and positioning a second part between the first and third part to isolate the third part from strain in the first part.
 56. A method of fabricating a frame for a display tile, said frame being of one piece or being split into two or more frame elements or strips, the method comprising: fastening the one piece frame or each frame element or strip to a first substrate and a second substrate forming part of the display tile; fabricating the one piece frame or each frame element or strip in 3 parts: gluing a first part to a lateral side of the first substrate, gluing a third part to a lateral side of the second substrate, and positioning a second part between the first and third part, the second part having a higher compliance than the first and third part thereby allowing the first and third part to be positioned in different planes.
 57. The method according to claim 55, further comprising the step of forming at least one opening which extends from an edge of the frame and extends across the first part and the second part of the frame.
 58. The method according to claim 56, further comprising the step of forming at least one opening which extends from an edge of the frame and extends across the first part and the second part of the frame.
 59. The method according to claim 55, wherein grooves are formed in the first part and/or the second part of the frame and/or grooves are formed on both sides of the frame.
 60. The method according to claim 56, wherein grooves are formed in the first part and/or the second part of the frame and/or grooves are formed on both sides of the frame.
 61. The method of claim 59, wherein the depth of the grooves is at least 50% of the thickness of the frame.
 62. The method of claim 60, wherein the depth of the grooves is at least 50% of the thickness of the frame.
 63. A display comprising at least one display tile and frame according to claim
 44. 